Ring stretcher



J. 0. POLLACK. I

' RING STRETCHER. APPLICATION HL'Ed Nov. 1, 1920.

1,432,783, Patented Oct. 24, 1922.

2 1 5. M11115 I am 1 a I Patented Get. 2%, lQZZT.

RING: STRETCHER.

Application filed November 1, 1920. Serial No. 421,056.

To (ZZZ whom it may concern:

Be it known that I, J osnrrr O. ToLLAoK, a citizen of the United States, residing at Chicago, county of Cook and State of Illinois, have invented certain new and useful Improvements in Ring Stretchers, of which the following is a description. I v

My invention relates to improvements 1n ring stretchers wherein it is desired to increase the internal diameter of a ring. The principal objects of my invention are to provide a device of the kind described, which may be operated quickly, safely and economically to enlarge the ring and to do so without any possibility of damaging the ring.-

Heretoi'ore it has been customary when enlarging rings to either place them upon a tapered mandrel and apply pressure to the ring to force it over the mandrel surtace, or to split and spread the ring and weld in an insert. The first method of operation, however, is liable to damage the ring, especially on its exterior surface. The second method is cumbersome and costly, and if the ring is engraved, either internally or externally, the inserted section must be similarly engraved after the enlargement is made so as to match the rest of the ring. The shape of the ring will also be changed by placing an insert between the spread ends, necessitating reshaping of the ring. Another objection to the method of cutting and inserting is that it requires additional precious metal and changes a seamless rmg into a seamed one after the enlargement.

My invention consists of a device for enlarging rings without the use of any additional precious metal, and wherein no part of the ring or setting is damaged in the operation. Many other objects and advantages of the construction herein shown and described will be obvious to those skilled in the art -from the disclosure herein made.

To this end my invention consists of the novel construction, arrangement and combination of parts herein shown and described and more particularly pointed out in the claims.

In the drawings, wherein like reference characters indicate like or corresponding parts,

F igure 1 is an elevation of the expansible mandrel;

Fig. 2 is an elevation of the expansible mandrel with a ring in place for enlargement;

Fig. 3 is a section taken substantially on l1ne 33 of Fig. 2;

Fig. 4: 1s an elevation of the expansible mandrel after expansion;

F 1g. 6 is a sectional view taken substantially on line 6-6 of F ig. 5.

Referring to thedrawings, 1 and 2 representmating elements cooperating to form a conical mandrel adapted to receive a rin A thereon. The mandrel elements each have plane surfaces 3 extending from end to end, and tapered exterior surfaces jl. Each of the elements 1 and 2 are grooved from end to end along their plane surfaces, as at 5, said grooves being in registry with each other when the elements are assembled with their plane surfaces 3 opposed to one another, and cooperating to term anv desired shape, such as circular, as shown in l i g. 3, or rectangular, etc.

A short rod or punch 6 is engageable with the groove 5, and is adapted to be torciblv driven through the split cone after a ring has been placed thereon, so as to separate the mandrel elements and thus enlarge the inner diameter of the ring, the ends oi? the punch being preferably tapered as at 7 to more readily allow it to enter the grooves 5.

The operation of stretchinga ring is as follows: The mandrel segments 1 and 2 are placed as shown in Fig. 1 so that their grooves are in registry with one another and the ring is placed over the mandrel. Then the rod or punch 6 is inserted in the grooves 5 between the segments and. forciblydriven through the mandrel with a hammer or other suitable instrument, as shown in Figs. 4-, 5 and G. The action causes the mandrel elements 1 and 2 to separate, enlarging the ring. Then the punch is removed, thering turned over on the mandrel, and the punch again driven through. Any desired amount of stretching may be accomplished by repeating the above operations. The registering grooves cooperate with the punch to prevent independent lateral movement ot the mandrel elements transversely to the direction of expansion, thus keeping them concentric to the ring.

It is apparent that any number of cone segments may be used to make up the mandrel, recesses being formed in each of the segments so that the recesses will register to form a single rod-receiving recess when as- 5 is a section taken on line 5-5 of sernbled, but I have found it preferableto use two segments because the fewer parts there are, the more cheaply the mandrel can be constructed.

The punch and mandrel may be made of any desired material of sufficienthardness, but I have found it highly satisfactory to make the parts of hard tool steel and polish the tapered ring-bearing surfaces. \Vhen the parts areso constructed of tool steel, there is little danger oftheir breaking, and

there-will be noscratching of the ring on the polished surface of the-mandrel.

IIQVIHQ; thus described my invention, it is ObVlOUS that various immaterial mod1'- icatio-ns maybe made in the same Withoutdeparting from the; spirit of my invention; hence I do not-Wish to be understood as l1m- .iting myself to the exact form, construction,

arrangement and combination of parts herein shown and described, or uses mentioned.

Vhat I claim as new and desire to secure by Letters Patent:

1. A ring stretcher comprising a split ex- .pansiblemember adapted to receive ring thereon, said member comprising a plurality larged.

" form depth therein, rod of uniform diameter insertable Within said. aligned grooves and tending to separate said elements vand enlarge the d ameter of SELlCl.(3OI1G,"Wl16FlJ the diameter of said :r ng" 1s permanently en- In testimony whereof, I have hereunto signed; my name in. thepresence of'tivo subscribing Witnesses, I

JOSEPH O. POLLACK.

Witnesses IiOY'WV. HILL,

:BERTHA "IIARTMANN. 

